The complex, located in the North Korean border town of Kaesong, is the largest employer in the North’s third-largest city, The New York Times reports. It generates $90 million a year in wages for the North Koreans working there — and its closing would affect as many as 300,000 people, South Korean analysts have estimated to The Times.

The North “will temporarily suspend the operations in the zone and examine the issue of whether it will allow its existence or close it,” the official Korean Central News Agency said, The Times reports.

King, the former chairman of the House Homeland Security Committee, told CNN that Pyongyang’s recent move “just adds more uncertainty. It shows more belligerence and more hostility on the part of the North Korean regime.

“It’s just a whole series of decisions and actions and statements over the past weeks and months, which is why everyone in our government is concerned about this. Not panicking, but certainly concerned — and treating it more seriously than the incidents of the past several years.”

King cautioned it would not be unwise to expect some military action from Pyongyang this week.

“I don’t want to be spreading panic here, but we have to be concerned and we have to be, as each day goes by, watching it more and more carefully.

“All of this has to be monitored,” he added. “We have to reassure our allies, South Korea, let Japan know that we’re standing with them.”

It’s even more critical that China be involved in “tamping down North Korea,” King said.

“There’s going to be more of a permanent U.S. presence in the Pacific as a result of what North Korea is doing — and the last thing China would want is a war in the Korean Peninsula, which ultimately would result in a South Korean victory and a united Korea, which I don’t think China wants at this stage.”

Perhaps the newest element to this all, King said, is the defiant position of South Korean President Park Geun-hye, who has warned that her country will strike back if attacked by the North.

“My understanding of President Park’s position is that she has made it clear that she will respond, she will retaliate — and it’s only a question of how strong the retaliation will be and what does North Korea do at that stage.

“I can’t blame South Korea for retaliating,” King told CNN. “They’re a sovereign nation, and if they’re being attacked by the North, President Park believes that she has to respond.

“That was an element that was not present in the past — and it’s something that we have to be very aware of.”